Methods: Between March 2014 and June 2017, 57 lung lesions in 56 patients (pts), median age 72 years (range 26–91) underwent ablative HT-SBRT: 34 pts (60.7%) for primary tumors and 22 pts (39.3%) for lung metastases. Staging was performed by contrast-enhanced chest CT and PET-CT scans. Immobilization was obtained with breast board and abdominal pressure mould mask. The planning target volume (PTV) included a margin of 10 mm in cranio-caudal direction and 5 mm in all other directions around the internal target volume (ITV), defined basing on the volumetric sum of the clinical target volumes of a free breathing planning CT and a pretreatment MVCT scan acquired in treatment position. According to tumor site, different schedules of RT were used: 60–70 Gy in 8–10 alternate fractions for peripheral lesions (n = 47) and 50 Gy and 60 Gy in 10 daily fractions for central (n = 10). Median BED10 was 96 Gy (range 75–119). Treatment-related toxicity was evaluated using CTCAE v4.0 scale. For the first year of follow-up, physical evaluation and chest CT were conducted every 2–3 months.

Results: Median GTV and PTV sizes were respectively 6.14 and 22.86 cc (range, 0.87–75.1 and 65.15–131.03). Median duration of RT was 15 days (range 10–20) and all pts were successfully treated with mild acute adverse events. Concurrent EGF-R-targeting TKIs were administered in 4 cases. With a median follow-up of 17 months (range 6–39) no ≥ G3 radiation pneumonitis or ≥ G2 esophagitis occurred; only 1 patient showed G2 non-cardiac chest pain, 2 pts G2 radiation pneumonitis. At the time of the analysis, 4 local failures were registered, resulting in Local Control (LC) rates of 97.1% for primary tumors and 84.8% for metastatic lesions; 49 pts are alive and 7 dead: 1y- and 2y- Overall survival rates were 96.6% and 87.8% for primary lesions and 94.1% and 79% for metastases, respectively.

Conclusions: HT-SBRT in primary or metastatic lung tumors demonstrates low risk of normal tissue complications and high rates of LC.